Experimental Research On Seismic Performance Of Slab Joints Of Shear Walls With Steel Tube Confined High-Strength Concrete

The concrete slab-shear wall structure is a structural system that replaces the beam slab floor with a flat floor.This structure system is beneficial to increase the floor clear height and improve the construction efficiency,facilitate industrial production and meet the requirements of building industrialization in our country.The traditional slab-wall structure system has poor ductility and insufficient seismic capacity under earthquake.In order to solve this problem,based on the research of the shear wall with steel tube confined high-strength concrete(STCHSC)with high bearing capacity,high rigidity and good ductility,our research group proposed an innovative "wall-slab structure incorporating STCHSC ".It has been proved that the innovative structure has good seismic performance in the shaking table test and it can be applied to high-rise and super-high-rise building structures.In addition,the damage of the structure in the shaking table test mostly occurs at the shear wall-slab joint,so it is necessary to strengthen the joint.In order to promote the application of wall-slab structure incorporating STCHSC in highrise and super high-rise building structures,improve the bearing capacity and seismic performance of nodes,and make up for the blank of design in the joint structure of this kind of structural system,two new types of STCHSC-coupling-slab joint are proposed as solutions to the problem.In this paper,their feasibility is proved by cycle loading tests and finite element theoretical analysis.The main research work and conclusions are as follows:1)Based on the characteristic that the steel tube in the shear wall at the joint blocks the two-layer and two-way rebar of the floor slab,two new types of STCHSC-coupling-slab joint are proposed: the floor rebar-anchor ring structure and the floor rebar anchor straight structure.2)Four specimens are designed and tested under cycle loading.The main parameters include the joint structure and the position of the shear wall where the joint is located.The cracking,yield,peak bearing capacity,failure process and failure morphology of the specimens under cycle loading are obtained.In addition,the key performance indexes such as deformation capacity,stiffness degradation and energy consumption capacity are also studied.The results show that the failure mode of the four specimens is mainly bending failure.The two joint structures proposed in this paper have no failure in the whole loading process and their force transfer and anchorage is reliable.The ductility and seismic resistance capacity of the joints are remarkable and reliable.3)The change law of the rebar's strain in the structural area is analyzed.For the floor rebar-anchor ring structure,the strain growth of the floor "U"-shaped rebar's strain lags behind the adjacent rebar slightly and can reach the yield before the piece yields.The force transmission path of the anchor ring is clear,and it has good anchorage and force transfer function.For the floor rebar anchor straight structure,the strain growth of the straight anchorage floor rebar is leading or flat compared to the adjacent rebar.It can also reach the yield before the specimen yields.The strain of the straight anchorage floor rebar extending into the shear wall at 25 times of the diameter is small.It proves that the anchorage and force transmission are direct and reliable.The working performance of the two kinds of joint structures' rebar is similar to that of the adjacent floor rebar.4)Compare the two types of joint.From the perspective of force transmission and anchoring,the floor rebar anchor straight structure is more direct than the floor rebar-anchor ring structure.From perspective of energy consumption,the floor rebar-anchor ring structure is stronger than the floor rebar-anchor ring structure in delaying the failure of the joint.5)Compare the positions of two kinds of shear walls where the joints are located.The seismic performance of the node specimen on the T-shaped shear wall is stronger than that of the I-shaped shear wall when the joint structure is the same.6)On the basis of the test,the ABAQUS analysis software is used to establish the joint model.The model is numerically analyzed and compared with the experimental results.The analysis results show that the finite element numerical analysis agrees with the experimental results,which can provide a reference for the design and research of engineering applications.